Sandals, including open- and close-toed shoes that include a sole and a strap system for retaining the sole against the bottom of the foot are well known in the art. The most simplistic footwear of this type is often composed of a sole and a toe/forefoot strap into which the user inserts their foot. Other sandals include a heel strap, and a more substantial top piece or “upper” encompassing the forefoot. The upper may fully enclose the foot or it may be open on the sides and/or top and include holes or passages for comfort etc. Examples of footwear in this art include items molded from one piece of material, as well as items built out of several components. In the latter case, the footwear is generally not designed to be disassembled and reassembled by the user. Although of course any footwear may be modified by a cobbler with the use of tools and new or alternative components may be fixed or attached essentially permanently with glue, rivets, nails, or other securing.
The field of footwear is crowded. However, most, if not all, footwear is limited in the sense that there are only limited occasions where any particular piece of footwear is acceptable. Style choices may dictate that a particular item of footwear is appropriate when the user is wearing a certain color of clothing. Further, social customs may dictate that only footwear of a sufficient level of formality (or informality) may be worn to any given event. Also, a user may wish to wear open or partially open toed shoes for comfort, yet some workplaces may require employees to wear fully closed shoes. Thus, the user is forced to purchase, maintain, store, and/or transport a large collection of footwear in order to be prepared for any situation.
The background art reveals, attempts to address this problem. For example, a sandal with interchangeable elements is disclosed in U.S. Pat. No. 3,902,259 to Cracco, issued Sep. 2, 1975. The '259 patent teaches a sandal comprised of several elements which can be replaced for purposes of repair or for change of color combination. However, the sandal of the '259 patent incorporates headless screws that must be adjusted and/or removed with tools in order for parts to be interchanged. Further, reassembling the sandal after disassembly requires the user to stack numerous elements to build the sole while simultaneously ensuring that various circular protrusions are aligned rotationally, horizontally, and vertically with corresponding holes. In sum, the sandal of the '259 patent demands a level of dexterity, coordination, and familiarity with tools that makes it inappropriate for children and others unaccustomed with using tools. Furthermore, such a design requires that the user have those tools with them whenever they desire an interchange, and it further creates the possibility that the screws will become stripped or otherwise stuck in the sandal, thereby rendering the interchangeable nature of the design, and possibly the sandal itself, useless.
The background art is also fundamentally limited in that the size of open-toed shoes and sandals is typically either fixed in length or adjustable via sliding cloth and/or hook-and-loop, Velcro-style straps. Either design choice exhibits flaws. For example, a breathable footwear piece with a fixed length strap can be seen in U.S. Pat. No. 6,993,858 to Seamans, issued Feb. 7, 2006. The strap on each shoe of a given size is identical and fixed in the '858 patent, so users who would like to periodically adjust the length of the strap for a tighter or looser fit of the shoe are unable to do so. In contrast, a piece of footwear that features adjustable straps appears in U.S. Pat. No. 6,256,906 to Matis et al., issued Jul. 10, 2001. As taught, the front strap is partially made of “leather, canvas, or other suitably durable material” that is presumably pliable enough to pass through a clip and bend back over itself to be secured by a clip or a Velcro-style fastener. However, such materials are highly prone to absorbing moisture and perspiration when worn next to the skin, which means their can exhibit foul odors and retain bacteria if not washed regularly. Additionally, hook-and-loop fasteners such as Velcro® tend to accumulate hair and dust after a few months of regular use. The loops can also become elongated or broken over time. Further, hook and loop-style fasteners often become attached to articles of clothing, especially loosely woven items like sweaters. Finally, fastening systems such as those seen in the '906 patent often feature clips and loops that are overly bulky and unsightly. In this case the user is faced with a choice of “one size fits all” or a cumbersome adjustable strap that degrades and becomes unsanitary over time.